This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The purposes of the research are to continue efforts to understand ion motion in modified FTMS traps, to construct traps guided by the theoretical considerations, to couple the trap with a high-pressure event (called the rf-only mode event) for collisional focusing of ions and MS/MS, and to test the effectiveness of the high-pressure event and an electrically compensated cell to study high-mass ions generated by MALDI. The goal of this core research project is to improve the detection and MS/MS performance for biomolecule ions with mass-to-charge ratios greater than a few thousand by making changes to the electrical properties of the trap rather than by increasing the magnetic field strength. We suggest that the instrumentation will not only be of interest for mid-sized proteins but also for peptides in proteomics applications.